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United States Patent |
5,549,881
|
Vaughan
,   et al.
|
August 27, 1996
|
Process for preparing a seeded high-silica zeolite having the faujasite
topology
Abstract
A process to make a seed high silica zeolite having a faujasite structure
and a silica to alumina ratio greater than 6, and containing tetrapropyl
ammonium and/or tetrabutyl ammonium trapped within the supercages of said
structure. The optimally seeds are aged for specific times.
Inventors:
|
Vaughan; David E. W. (Flemington, NJ);
Strohmaier; Karl G. (Port Murray, NJ)
|
Assignee:
|
Exxon Research and Engineering Company (Florham Park, NJ)
|
Appl. No.:
|
347004 |
Filed:
|
November 29, 1994 |
Current U.S. Class: |
423/703; 423/705; 423/709; 423/DIG.21 |
Intern'l Class: |
C01B 039/20 |
Field of Search: |
423/703,705,707,709,DIG. 21
502/79
|
References Cited
U.S. Patent Documents
4166099 | Aug., 1979 | McDaniel et al. | 423/709.
|
4340573 | Jul., 1982 | Vaughan et al. | 423/DIG.
|
4608236 | Aug., 1986 | Strack et al. | 502/79.
|
4631262 | Dec., 1986 | Altomare | 423/709.
|
4657748 | Apr., 1987 | Vaughan et al. | 423/707.
|
4714601 | Dec., 1987 | Vaughan | 423/707.
|
4879103 | Nov., 1989 | Vaughan | 423/705.
|
4931267 | Jun., 1990 | Vaughan et al. | 423/705.
|
4965059 | Oct., 1990 | Vaughan et al. | 423/707.
|
5154904 | Oct., 1992 | Kleinschmit et al. | 423/709.
|
5206005 | Apr., 1993 | Vaughan et al. | 423/707.
|
Primary Examiner: Bell; Mark L.
Assistant Examiner: Sample; David
Attorney, Agent or Firm: Hantman; Ronald D.
Parent Case Text
This is a continuation of application Ser. No. 200,987, filed Feb. 24, 1994
now abandoned.
Claims
What is claimed is:
1. A process for preparing the aluminosilicates, ECR-4 or ECR-32, having a
faujasite structure and a composition, in terms of mole ratios of oxides,
in the range:
0.2 to 0.80 T.sub.2 O:0.20 to 0.8 Na.sub.2 O:Al.sub.2 O.sub.3 :6 to 15
SiO.sub.2 :xH.sub.2 O
wherein T represents an organic ammonium template trapped in supercages of
said zeolite and x represents 0 or an integer from 1 to 20, wherein said
process comprises:
(a) preparing a reaction mixture comprising an oxide of sodium, a
bis-(2-hydroxyethyl) dimethyl or tetrapropyl or tetra hydroxypropyl or
tetrabutyl or tetra hydroxy-butyl organic ammonium salt, or combinations
thereof, water, a source of silica, a source of alumina, and sodium
aluminosilicate nucleating seeds, said reaction mixture having a
composition, in terms of mole ratios of oxides, within the following
ranges:
______________________________________
(Na, T).sub.2 O:Al.sub.2 O.sub.3
3 to 15
SiO.sub.2 :Al.sub.2 O.sub.3
9 to 36
H.sub.2 O:Al.sub.2 O.sub.3
120 to 500
______________________________________
where T represents the cation of the organic ammonium template, and said
seeds being aged between 6 and 16 days and present in an amount to yield
0.1 to 10 mole percent of the total final alumina content in said
aluminosilicate;
(b) blending the reaction mixture sufficiently to substantially form a
mixture;
(c) maintaining the reaction mixture at between about 80.degree. C. and
160.degree. C. under autogenous pressure for a sufficient period of time
to form crystals of said aluminosilicate; and
(d) recovering said aluminosilicate crystals.
2. The process of claim 1 wherein the source of silica is a colloidal
silica and the sources of alumina are hydrated alumina and an aluminum
salt selected from the group consisting of the chloride, sulfate and
nitrate salts.
3. The process of claim 2 wherein the reaction mixture is maintained
between 90.degree. and 140.degree. C.
4. The process of claim 1 wherein said seeds are aged between 8 and 14
days.
5. The process of claim 4 wherein said seeds are aged between 10 and 12
days.
Description
FIELD OF THE INVENTION
The present invention relates to an improved seeding process for the
synthesis of a high silica zeolite having the faujasite structure and
containing organic tetrapropyl and, or tetrabutyl ammonium ions and/or bis
(2-hydroxyethyl) dimethyl ammonium. The product may be employed in
catalytic, absorbent or separation applications, particularly in cracking
and hydrocracking catalysts.
BACKGROUND OF THE INVENTION
Large pore zeolites with high silica to alumina ratios, i.e., of at least
four, are desirable because of their particular catalytic selectivity and
their thermal stability; the latter is a property particularly important
when the zeolite is used as catalyst or in adsorption procedures wherein
exposure to high temperatures would be expected. Although faujasite
zeolites having silica to alumina ratios of less than four can be readily
synthesized by a variety of methods, as disclosed, e.g., in U.S. Pat. Nos.
2,882,244 and 4,178,352, methods for preparing faujasite polymorphs of
higher ratios generally involve several weeks of crystallization and
result in poor yields of product, as reported by Kacirek, J. Phy. Chem.,
79, 1589 (1975).
The use of quaternary ammonium salts as templates or reaction modifiers in
the preparation of synthetic crystalline aluminosilicates (zeolites),
first discovered by R. M. Barrer in 1961, has led to preparation of
zeolites with high silica to alumina ratios which are not found in nature.
A review provided by Barrer in Zeolites, Vol. I, p. 136 (October, 1981)
shows the zeolite types which are obtained using various ammonium organic
bases as cation. In addition, Breck, Zeolite Molecular Sieves, John Wiley
(New York, 1974), pp. 348-378, provides a basic review of zeolites
obtained using such ammonium cations in the synthesis thereof, as does a
review by Lok et al. (Zeolites, 3, p. 282, 1983)).
The Si/Al ratios of a variety of readily synthesized NaY materials
(SiO.sub.2 /Al.sub.2 O.sub.3 <6) can be increased by a wide range of
chemical or physical chemical treatments. However, these processes usually
involve removal of Al from the zeolite framework and creation of a
metastable defect structure, followed by filling the defects with Si from
another part of the structure by further chemical treatments or
hydrothermal annealing. Typical treatments use steam, e.g., U.S. Pat. No.
3,293,192; acid leaching, e.g., U.S. Pat. No. 3,506,400; treatments with
EDTA, e.g., U.S. Pat. No. 4,093,560; treatment with SiCl.sub.4 (Beyer and
Belenyakja, Catalysis by Zeolites S, p. 203 (1980), Elsevier Press.);
treated with CHF.sub.3, i.e., 4,275,046; or treated with other chemicals.
The products are often called "ultra stable" faujasites (cf. Maher and
McDaniel Proceedings Intl. Conference on Molecular Sieves, London, 1967)
because of their very high thermal and hydrothermal stability. However,
such chemical processing often yields variable products, requires
multi-step processing, often using highly corrosive environments, and
usually involves a yield debit in the form of partly collapsed or blocked
zeolite product. Few of the modified materials have the product quality of
the starting sample because the process of modification involves partial
destruction of the lattice and/or deposition of detrital reaction products
within the pores of the structure. This usually results in the development
of a secondary meso pore structure (Lohase et al, Zeolites, 4, p. 163
(1984)) which, although of some catalytic interested, will be less
controlled and selective then the parent structure. Other methods of so
called secondary synthesis using (NH.sub.4).sub.2 SiF.sub.6 in aqueous
solution have also been demonstrated to yield higher silica zeolites (U.S.
Pat. No. 4,503,023). Methods of directly synthesizing high silica
faujasites, without such "secondary synthesis" treatments, would therefore
be useful in optimizing both the zeolite product and the process for its
production.
Although the disclosed composition is quite thermally stable in its own
right because of its high silica content, that thermal stability makes the
inventive composition particularly useful as a starting material for the
dealumination processes described above. Since the number of aluminum
atoms in the framework of the inventive composition is lower than in
zeolite Y, removal of these atoms causes less framework metastability
during dealumination, allowing the formation of near pure silica
faujasites.
The objective of the present invention is to develop improved faujasite
preparation methods yielding high silica materials, where the organic
templates are not locked into the small cavities in the structure, but are
instead present in the large "super cages" from which they can be readily
removed without disruption and degradation of the host lattice. One such
group of faujasite polymorphs are designated ECR-32 and ECR-4 (see U.S.
Pat. Nos. 4,714,601, 4,965,059, and 4,931,267). The principal objective of
this invention is to significantly improve the processes for making such
materials.
SUMMARY OF THE INVENTION
The present invention is an improved process to prepare by direct synthesis
a high silica crystalline zeolite having the faujasite structure and a
SiO.sub.2 /Al.sub.2 O.sub.3 mole ratio of at least four. The improvement
involves the discovery that the exact nature of the "seed" component may
dramatically effect the crystallization time of the said ECR-4/32. At low
ratios of product such as the prior art synthetic faujasite materials
designated X and Y, the seed age times do not materially influence the
crystallization times. Surprisingly, in the case of ECR 4/32, an optimum
seed aging reduces the time of crystallization by a factor of up to three
or four, greatly reducing the cost of the product. The chemical
composition for this zeolite product, expressed in terms of mole ratios of
oxides, is in the range:
0.2 to 0.8 T.sub.2 O:0.2 to 0.8 Na.sub.2 O:Al.sub.2 O.sub.3 :6 to 18
SiO.sub.2 :xH.sub.2 O
wherein T represents bis (2hydroxyethyl)-dimethyl ammonium, tetrapropyl and
or tetrabutyl-ammonium organic cation, and x represents 0 or an integer
from 1 to 25, depending on composition and degree of hydration. The more
preferred composition for the zeolite is in the range: 0.2 to 0.8 T.sub.2
O:0.2 to 0.6 Na.sub.2 O:Al.sub.2 O.sub.3 :6 to 16 SiO.sub.2 :xH.sub.2 O.
The most preferred composition has the same molar oxide ratio as does the
more preferred composition save the SiO.sub.2 /Al.sub.2 O.sub.3 ratio
which is 8 to 14.
The aluminosilicate herein may be used as a sorbent or as a catalyst, e.g.,
as a hydrocarbon conversion catalyst for, e.g., cracking, hydrocracking,
reforming, paraffin isomerization, aromatization and alkylation. When the
product is used as a catalyst, [the alkyl or hydroxyalkylammonium cations
trapped in the super cages of the faujasite structure are first removed by
calcination,] then the product may be exchanged with cations from Groups
II through VIII of the Periodic Table to remove the excess sodium ions
which may be undesirable.
The process to the zeolite includes the steps of preparing a reaction
mixture comprising an oxide of sodium, a bis (2-hydroxyethyl)dimethyl,
tetrapropyl and/or hydroxypropyl (or similar tetrabutyl) ammonium salt,
water, a source of silica, a source of alumina, and optimized sodium
aluminosilicate nucleating seeds of this invention.
The reaction mixture has a composition, in terms of mole ratios of oxides,
within the following ranges:
______________________________________
(Na, T).sub.2 O:Al.sub.2 O.sub.3
3 to 15
SiO.sub.2 :Al.sub.2 O.sub.3
9 to 36
H.sub.2 O:Al.sub.2 O.sub.3
120 to 500
______________________________________
where T represents a tetra-alkyl or hydroxyalkyl ammonium cations and the
seeds being present in an amount to yield 0.1 to 10 mole percent of the
total final alumina content in the zeolite.
For optimum results, a specific seed composition must be aged for specific
times and temperatures. The reaction mixture is blended with the seed
slurry sufficiently to form a substantially homogeneous mixture, which is
maintained at a temperature between about 80.degree. C. and 160.degree. C.
under autogenous pressure for a sufficient period of time to form crystals
of the aluminosilicate zeolite. The zeolite crystals are then recovered by
filtration, centrifugation or other means. The optimum seed mixture is
defined by composition, age time and age temperature. Although increasing
the seed age temperature reduces the time to maturity, higher temperatures
quickly grow the seeds into an ineffective size. The requirement for tight
control increases with increasing batch size, making control, close
temperature and aggitation necessary on a commercial scale.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the effect of seed age and temperature on zeolite
crystallization rates exemplified in Examples 1 through 18.
FIG. 2 shows optimun seed age as a function of seed Si/Al.sub.2 ratio.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The aluminosilicate herein synthesized generally will have the formula, in
terms of mole ratios of oxides, in the range:
0.2 to 0.8 T.sub.2 O:0.2 to 0.8 Na.sub.2 O:Al.sub.2 O.sub.3 :6 to 18
SiO.sub.2 :xH.sub.2 O
or most preferably 0.40 to 0.80 T.sub.2 O:0.2 to 0.6 Na.sub.2 O:Al.sub.2
O.sub.3 :8 to 14 SiO.sub.2 :H.sub.2 O where x is 0-20 and T is tetraalkyl
ammonium cations preferably selected from tetrapropyl, tetrabutyl and bis
(2-hydroxyethyl) dimethyl ammonium. Part of the aluminum in such
compositions may be partly replaced by cations of other metals(m), such as
Ga, Ge, Fe Cr, Ti, Mn, V, P, B, Ni, Co and Zn, although never to exceed
30% of the framework Al component.
These alkyl ammonium cations are relatively large ions which are not
trapped within the small sodalite cages of the aluminosilicate faujasite
structure, but are present in the super cages of the structure, as shown
by the low temperature at which the organic template is removed from the
supercage.
Minor variations in the mole ratios of the oxides within the ranges given
in the chemical formulas above do not substantially alter the structure or
properties of the zeolite. In addition, the number of waters of hydration
x in the formula will not be the same for each preparation and will depend
mainly on the degree to which the aluminosilicate is dried, and the amount
of template. Generally, increasing the SiO.sub.2 /Al.sub.2 O.sub.3 ratio
of the reaction gel increases the SiO.sub.2 /Al.sub.2 O.sub.3 ratio of the
product.
In order to convert the inventive high silica faujasitic zeolites into
catalysts, the organic ions in the "super cage" of the zeolite are first
exchanged, desorbed or degraded at high temperature. By comparison to
other zeolites having ammonium ions trapped in their smaller cages, the
temperature of calcination is significantly lower. As even large
decomposition organic fragments may easily diffuse through the large pores
of the zeolite ECR-4/32, bond breakage and lattice degradation associated
with the escape of such fragments from the smaller cages is generally not
observed in ECR-4/32.
The exchangeable cations, which may partially or fully replace the sodium
ions wherever they may be found together with the organic ammonium ions in
the large cages of the faujasite structure, may be cations of metals from
any one of Groups I through VII of the Periodic Table (such designation
being explained in Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd
Edition, r.8, page 94(1965)) including rare earth metals, depending on the
end use desired. Preferably, the cations will be mono-, di- and trivalent
metal cations, particularly from Groups I, II or III of the PeriodicTable,
such as barium, calcium, cesium, lithium, magnesium, potassium, strontium,
zinc, or the like, or hydrogen, rare earth metals, or ammonium ions.
Optimized basic catalysts can be obtained by exchanging with sodium
cations after removal of the alkylammonium cations. The presence of these
exchangeable cations will generally not cause a substantial alteration of
the basic crystal structure of the aluminosilicate. Particularly preferred
are mono- and divalent cations, as they are more easily included in the
pores of the zeolite crystal. Any ion exchange technique may be employed
such as those discussed, for example, in U.S. Pat. No. 3,216,789, but may
include aqueous and non-aqueous solvents and molten salts.
The aluminosilicate herein may be prepared by a process in which a reaction
mixture, generally a slurry, is formed comprised of an oxide of sodium,
water, the organic ammonium salt, a source of silica, a source of alumina,
and sodium zeolitic (aluminosilicate) nucleating seeds. The oxide of
sodium may be, e.g., sodium hydroxide, and the organic ammonium salt may
be a sulfate, nitrate, hydroxide or halide salt. Often it is preferably a
halide such as the chloride, iodide or bromide salt because of lower cost.
The silica may be derived from sources such as, e.g., silica gels, silicic
acid, aqueous colloidal silica sols as described, for example, in U.S.
Pat. No. 2,574,902, reactive amorphous solid silicas such as fume silicas
and chemically precipitated silica sols, and potassium or sodium silicate,
preferably sodium silicate. The alumina may be derived from sources such
as, e.g., activated alumina, alumina trihydrate, sodium aluminate, alum,
kaolin, metakaolin or the like. It is noted that the sodium oxide may be
provided not only directly be adding, e.g., sodium hydroxide to the
mixture, but also indirectly from the source of silica and/or the source
of alumina if, for example, sodium silicate and sodium aluminate (prepared
by dissolving NaOH and Al.sub.2 O.sub.3.3H.sub.2 O in water) are
respectively employed as at least one of the silica and alumina sources.
The preferred sources of alumina are hydrated alumina and an aluminum salt
selected from the chloride, sulfate and nitrate salts.
The aluminosilicate nucleating seeds for the reaction mixture, also known
as zeolitic nucleation centers, comprise of a slurry of zeolite solids
having the following components: SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O
and H.sub.2 O. Generally, the seeds will have an average particle size
less than 0.05 microns. The composition of the nucleating seeds in the
slurry may be in the approximate ranges, in terms of mole ratios of
oxides, as follows:
4 to 30 Na.sub.2 O:1 to 9 Al.sub.2 O.sub.3 :3 to 30 SiO.sub.2 :250 to 2000
H.sub.2 O
Such slurries of nucleating seeds may be prepared in the composition ranges
disclosed in U.S. Pat. Nos. 3,808,326 and 4,178,352, the disclosures of
which are incorporated by reference. In general, the preparation procedure
involves mixing of sodium silicate, sodium aluminate and water together
and aging the resulting slurry. The optimization of this synthesis
requires the specific aging of this seed component within relatively
narrow ranges--quite unlike the prior art broad disclosures. Such specific
aging is well defined in FIG. 1, as is the influence of specific seed
compositions (FIG. 2).
The amount of nucleating seeds present in the reaction mixture is expressed
in terms of the percentage of the total molar alumina content in the
aluminosilicate product which is ultimately recovered on crystallization.
Thus, for example, if 5 molar percent of the nucleating seeds is added to
the mixture, the seeds are contributing 5% of the total molar amount of
alumina in the zeolite product recovered. In general, the seeds are
present in an amount to yield 0.1 to 20 mole percent of the total final
alumina content of the product, and preferably 2 to 10 mole percent.
Slurries comprising recycled products of the process disclosed herein will
also serve as nucleation seeds, but may not yield the reported shortest
crystallization times of this invention.
The relative amounts of ingredients in the reaction mixture will be such
that the mixture has a composition, in terms of mole ratios of oxides,
within the following ranges:
______________________________________
Oxide Constituents
Ranges of Mole Ratios
______________________________________
(Na, T).sub.2 O:Al.sub.2 O.sub.3
3 to 15
SiO.sub.2 :Al.sub.2 O.sub.3
9 to 36
H.sub.2 O:Al.sub.2 O.sub.3
120 to 500
______________________________________
where T represents an organic ammonium group as described above.
Preferably, the mole ratio of H.sub.2 O to Al.sub.2 O.sub.3 in the
reaction mixture ranges from 200 to 400, and the mole ratio of SiO.sub.2
to Al.sub.2 O.sub.3 from 15 to 30. When metallic alumino silicates are the
target product Al in the above ratios will be replaced by (Al+m) and the
ratio of m:(Al+m) will not exceed 0.3.
The order of mixing the ingredients is not essential, and all ingredients
may be added simultaneously. In one preferred method of preparation a
colloidal silica solution, a slurry of nucleating seeds and an organic
ammonium halide solution are added to a blender, followed by slow
addition, with mixing, of a sodium aluminate solution and an alum
solution. Additional water is added to the resulting slurry. The reaction
mixture is ordinarily prepared in a container made of glass, TEFLON, or
metal or the like which should be closed to prevent water loss.
After the reaction mixture is formed it may be homogenized by thorough
blending so as to be substantially homogeneous in texture. This step is to
ensure that the aluminosilicate product ultimately obtained is not a
mixture of products and thus impure. The mixing may take place in any
vessel in which complete mixing is effected, e.g., a blender, in line pump
or other highly agitated system.
The homogenized mixture is then placed in a reactor, ordinarily one which
can withstand elevated pressures such as a tetrafluoroethylene-lined jar
or an autoclave, where it is maintained at a temperature of between about
80.degree. C. and 160.degree. C., preferably 90.degree. and 140.degree. C.
For commercial purposes, preferably no greater than 140.degree. C. The
exact temperature will depend, for example, on the amount of sodium oxide
present and the length of time employed for reaction. When the homogenized
mixture is heated it is maintained at autogenous pressures which will
depend on the temperature employed. Lower pressures of 1 atm may be
adequate for temperatures at the lower range but at higher temperatures up
to 160.degree. C. pressures of up to about 3 to 10 atm or higher may be
achieved. The amount of time required for heating will depend mainly on
the temperature employed, so that at 100.degree. C. the heating age time
will be greater than at 120.degree. C. The specific preferred reaction
temperature will depend on the economics of autoclave use and
productivity.
When the aluminosilicate crystals have been obtained in sufficient amount,
they are recovered by centrifugation or filtration from the reaction
mixture and are then washed, preferably with deionized water, to separate
them from the mother liquor. The washing should continue, for best purity
results, until the wash water, equilibrated with the product, has a pH of
between about 9 and 12. After the washing step the zeolite crystals may be
dried as in a kiln, followed by calcination to remove the alkylammonium
ions.
The aluminosilicate ECR-32 of this invention may be used as a sorbent or as
a catalyst, e.g., in a hydrocarbon conversion process. ECR-41/32, having a
faujasite structure and a mole ratio of SiO.sub.2 /Al.sub.2 O.sub.3 of at
least six with organic ammonium templates removable below about
400.degree. C., as shown by thermogravimetric analysis, can be used in
paraffin isomerization, aromatization, and alkylation and in the
reforming, hydrocracking and cracking and isomerization of lube stocks,
fuels and crude oils. To be employed for these applications, the
aluminosilicate usually is first calcined to remove the alkylammonium
template. Then cation exchanged to a catalytically active form.
Dealumination and demetallation may be an important part of such
preparation procedures. The said ECR 4/32 is then heated to temperatures
of up to about 500.degree. C. or more until most of the water of hydration
is removed.
ANALYTICAL PROCEDURES
A zeolite may be definitively identified by its x-ray diffraction pattern
and chemical composition obtained by a variety of bulk chemical analyses.
The unit cell measurement for various faujasites, in particular, has
become a measurement (ASTM method D-3942-80) standardized to reflect the
Si/Al ratio of the pure sodium form synthetic faujasite. Unfortunately,
substitution of cations other than Na.sup.+ into faujasite renders the
established "unit cell vs. composition" relationships valueless. Since
ECR-4/32 contains organic cations in addition to Na.sup.+, unit cell
correlations obtained by these methods have little value, until the said
ECR-4/32 is first purged of the organic template, then sodium exchanged.
Such values for Na-ECR-32 are included in the examples. Na-ECR-4/32 may be
defined by the following essential diffraction lines.
TABLE A
______________________________________
MAJOR X-RAY DIFFRACTION PEAKS FOR ECR-32
d Spacing (.ANG.)
Relative Intensity
______________________________________
14.05-14.20 VS
8.60-8.70 M
7.32-7.44 W
7.00-7.15 W
5.58-5.65 S
4.68-4.75 M
4.30-4.35 M
3.85-3.90 W
3.70-3.75 M-S
3.40-3.45 W
3.25-3.30 M
2.97-3.05 W
2.87-2.90 M-W
2.81-2.84 M
2.72-2.75 W
2.59-2.63 W
2.34-2.37 W
______________________________________
VS = 100-80; S = 80-40; M = 40-15; W = 3-15 in absolute value ranges)
A valuable indirect measurement of Si/Al ratio has been developed recently
which, to a first approximation, is not significantly influenced by
variable cations contents. Known as .sup.29 Si- magic angle spinning
nuclear magnetic resonance (MSA-NMR), it measures the relative number of
Si atoms surrounded by 4 Al, (3Al+1Si), (2Al+2Si), (1Al+3Si) and 4Si, from
which the total average Si/Al ratio can be readily calculated (Melchior et
al, J. Amer. Chem. Soc., v. 104, p. (1982)). Compared with the
conventional Y faujasite, ECR-4/32 compositions may clearly be
differentiated on the basis of relative peak values, vis., in the case of
ECR-4/32 the number of Si atoms having zero and one Al neighbors is
greater than the number of Si atoms having 2 and 3 Al neighbors. For
zeolite Y the reverse is true.
ECR-32: Si(0Al)+Si(1Al)>Si(2Al)+Si(3Al)
Zeolite Y: Si(OAl)+Si(1Al)<Si(2Al)+Si(3Al).
It should be apparent that .sup.29 Si-MAS-NMR spectra give a more reliable
indication of the number of Si and Al atoms in a sample then would a
comparable bulk chemical test. The MAS-NMR ignores detrital or adsorbed
and dissolved silicon and aluminum atoms since it measures those atoms
only when they are in particular spatial relationship to each other. Bulk
chemical tests have no way to make such a differentiation.
A further differentiating characteristic of ECR-4/32 is that the organic
template is located in the "super cage" rather than the smaller sodalite
cage. Although this can be demonstrated using .sup.13 C-MAS-NMR, it is
also readily demonstrated by a simple thermogravimetric experiment in
which a small sample is heated in a controlled fashion and the weight loss
on template "burn off" at high temperature is recorded.
EXAMPLE 1
Preparation of Nucleant Seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =12.5.
A nucleant seed solution of stoichiometry,
13.33 Na.sub.2 O:Al.sub.2 O.sub.3 :12.5 SiO.sub.2 :267 H.sub.2 O,
was prepared by first preparing a sodium aluminate solution by dissolving
60.0 g. NaOH in 100 ml. distilled water. To this solution 12.0 g. of
aluminum trihydrate (Al.sub.2 O.sub.3.3H.sub.2 O; 156.01 g./mole; ALCOA
C-31) was added and the solution was heated with stirring on a hot
plate/magnetic stirrer until the alumina dissolved. The solution was
cooled to room temperature. To a one liter blender was added 201.6 g. of N
brand sodium silicate solution ((P.Q. Corp. 8.9% Na.sub.2 O; 28.7%
SiO.sub.2) and 100 g. of distilled water. With vigorous stirring the
sodium aluminate solution was slowly poured in and then rinsed in with
distilled water. Enough distilled water was then added to bring the total
weight of the mixture to 500 g. The mixture was again homogenized and then
stored in a closed plastic or Teflon container. It was allowed to age at
room temperature 22.degree. C. for 2 to 49 days before use.
EXAMPLEs 2-12
Preparation of ECR-32 using ambient temperature aged seeds.
A sodium aluminate solution was prepared by dissolving 59 g. NaOH in 100
ml. distilled water. To this solution 75 g. of aluminum trihydrate
(Al.sub.2 O.sub.3.3H.sub.2 O; 156.01 g./mole; ALCOA C-31) was added and
the solution was heated with stirring on a hot plate/magnetic stirrer to a
mild boil until the alumina dissolved. The solution was then cooled to
room temperature and distilled water added to a final weight of 250 g.
A series of reactant gels were prepared having the stoichiometry:
3.6 TPA.sub.2 O:1.2 Na.sub.2 O:Al.sub.2 O.sub.3 :18 SiO.sub.2 :275 H.sub.2
O:0.99 Na.sub.2 O.sub.4.
All gels were identically prepared except for the age of the nucleant
seeds. To a 2 liter plastic beaker were added, while mixing with a
spatula, 324.6 g. of 40% colloidal silica (HS-40, dupont Ludox; 40 wt. %
SiO.sub.2), 83.7 g. nucleant seeds (aged 2-49 days), 472.2 g. of aq. 40%
TPAOH,, 38.3 9. sodium aluminate solution, as made above, 55.1 g. of 50%
Al.sub.2 (SO.sub.4).sub.3.17H.sub.2 O solution, and enough distilled water
to bring the total weight of mixture to 1000 g. The white gel was
transferred to a blender and thoroughly homogenized. The gel was then
placed in 1000 ml. Teflon bottle and reacted in an air oven at 100.degree.
C.
Samples were taken periodically, filtered and washed with distilled water.
Crystallization was followed by powder X-ray diffraction until completed.
The following Table 1 lists the crystallization time of each experiment
and clearly shows the preferred seed age time of 8 to 18 days. The
optimization at this seed composition is shown graphically in FIG. 1.
TABLE 1
______________________________________
Example Seed Age Cryst. Time
______________________________________
2 2 21
3 5 17
4 9 8
5 12 7
6 12 7
7 14 8
8 14 9
9 18 11
10 22 14
11 37 19
12 49 14
______________________________________
EXAMPLE 13
Preparation of Nucleant Seeds Aged at 50.degree. C.
The seed composition of Example 1 was remade, and then stored in a closed
Teflon container in an air oven at 50.degree. C. for 2 to 14 days before
use.
EXAMPLES 14-18
Preparation of ECR-32 using 50.degree. C. Aged Seeds
A sodium aluminate solution was prepared by dissolving 59 g. NaOH in 100
ml. distilled water. To this solution 75 g. of aluminum trihydrate
(Al.sub.2 O.sub.3.3H.sub.2 O; 156.01 g./mole; ALCOA C-31) was added and
the solution was heated with stirring on a hot plate/magnetic stirrer to a
mild boil until the alumina dissolved. The solution was then cooled to
room temperature and distilled water added to a final weight of 250 g.
A series of reactant gels were prepared having the stoichiometry:
3.6 TPA.sub.2 O:1.2 Na.sub.2 O:Al.sub.2 O.sub.3 :18 SiO.sub.2 :275 H.sub.2
O 0.99 Na.sub.2 SO.sub.4.
All gels were identically prepared except for the age time of the nucleant
seeds of Example 13. To a 2 liter plastic beaker were added, while mixing
with a spatula, 324.6 g. of 40% colloidal silica (HS-40, dupont Ludox; 40
wt. % SiO.sub.2), 83.7 g. nucleant seeds (Example 13), 472.2 g. of aq. 40%
TPAOH, 38.3 g. sodium aluminate solution as made above, 55.1 g. of 50%
Al.sub.2 (SO.sub.4).sub.3.17H.sub.2 O solution, and enough distilled water
to bring the total weight of mixture to 1000 g. The white gels were
transferred to a blender and thoroughly homogenized. The gels were then
placed in 1000 ml. Teflon bottle and reacted in an air oven at 100.degree.
C.
Samples were taken periodically, filtered and washed with distilled water.
Crystallization was followed by powder X-ray diffraction until completed.
The following Table 2 lists the crystallization time of each example and
clearly shows the preferred seed age time of 9 to 18 days for room
temperature aged seeds and 2 to 14 days for 50.degree. C. aged seeds.
TABLE 2
______________________________________
Crystallization
Example #
Seed age (days)
Seed age temp.
time (days)
______________________________________
14 2 50.degree. C.
7
15 4 50.degree. C.
9
16 6 50.degree. C.
7
17 10 50.degree. C.
4
18 14 50.degree. C.
5
______________________________________
EXAMPLE 19
Preparation of Nucleant Seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =17.5
A nucleant seed solution of stoichiometry,
13.33 Na.sub.2 O:Al.sub.2 O.sub.3 :17.5 SiO.sub.2 :267 H.sub.2 O,
was prepared by first preparing a sodium aluminate solution by dissolving
48.5 g. NaOH in 100 ml. distilled water. To this solution 11.5 g. of
alumina trihydrate (Al.sub.2 O.sub.3.3H.sub.2 O; 156.01 g./mole; ALCOA
C-31) was added and the solution was heated with stirring on a hot
plate/magnetic stirrer until the alumina dissolved. The solution was
cooled to room temperature. To a one liter blender was added 269.8 g. of N
brand sodium silicate solution (P.Q. Corp. 8.9% Na.sub.2 O; 26.7%
SiO.sub.2) and 60 g. of distilled water. With vigorous stirring the sodium
aluminate solution was slowly poured in and then rinsed in with distilled
water. Enough distilled water was then added to bring the total weight of
the mixture to 500 g. The mixture was again homogenized and then stored in
a closed plastic or Teflon container. It was allowed to age at room
temperature for 2 to 32 days, or aged at 50.degree. C. for 1 to 6 days
before use.
EXAMPLES 20-25
Preparation of ECR-32
A sodium aluminate solution was prepared by dissolving 59 g. NaOH in 100
ml. distilled water. To this solution 75 g. of aluminum trihydrate
(Al.sub.2 O.sub.3.3H.sub.2 O; 156.01 g./mole; ALCOA C-31) was added and
the solution was heated with stirring on a hot plate/magnetic stirrer to a
mild boil until the alumina dissolved. The solution was then cooled to
room temperature and distilled water added to a final weight of 250 g.
A series of reactant gels were prepared having the stoichiometry:
3.6 TPA.sub.2 O:1.2 Na.sub.2 O:Al.sub.2 O.sub.3 :18 SiO.sub.2 :275 H.sub.2
O: 0.99 Na.sub.2 SO.sub.4.
All gels were identically prepared except for the age time and aging
temperature of the nucleant seeds. To a 250 ml. plastic beaker were added,
while mixing with a spatula, 42.5 g. of 40% colloidal silica (HS-40,
dupont Ludox; 40 wt. % SiO.sub.2), 11.9 g. nucleant seeds (Example 18),
63.7 g. of aq. 40% TPAOH, 5.17 g. sodium aluminate solution as made above,
7.44 g. of 50% Al.sub.2 (SO.sub.4).sub.3.17H.sub.2 O) solution, and enough
distilled water to bring the total weight of mixture to 135 g. The white
gels were transferred to a blender and thoroughly homogenized. The gels
were then placed in 125 ml. Teflon bottle and reacted in an air oven at
100.degree. C.
Samples were taken periodically, filtered and washed with distilled water.
Crystallization was followed by powder X-ray diffraction until completed.
The following Table 3 lists the crystallization time of each example and
clearly shows the preferred seed age time of 8 to 32 days for room
temperature aged seeds.
TABLE 3
______________________________________
Crystallization
Example #
Seed age (days)
Seed age temp.
time (days)
______________________________________
20 8 22.degree. C.
5
21 24 22.degree. C.
4
22 32 22.degree. C.
5
23 1 50.degree. C.
14
24 3 50.degree. C.
14
25 6 50.degree. C.
10
______________________________________
In this case the ambient temperature aged seeds are clearly preferred.
EXAMPLE 26
Preparation of Nucleant Seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =15.
A nucleant seed solution of stoichiometry,
13.33 Na.sub.2 O:Al.sub.2 O.sub.3 :15 SiO.sub.2 :267 H.sub.2 O,
was prepared by first preparing a sodium aluminate solution by dissolving
54.2 g. NaOH in 100 ml. distilled water. To this solution 11.8 g. of
alumina trihydrate (Al.sub.2 O.sub.3.3H.sub.2 O;156.01 g./mole; ALCOA
C-31) was added and the solution was heated with stirring on a hot
plate/magnetic stirrer until the alumina dissolved. The solution was
cooled to room temperature. To a one liter blender was added 236.5 g. of N
brand sodium silicate solution (P.Q. Corp. 8.9% Na.sub.2 O;26.7%
SiO.sub.2) and 80 g. of distilled water. With vigorous stirring the sodium
aluminate solution was slowly poured in and then rinsed in with distilled
water. Enough distilled water was then added to bring the total weight of
the mixture to 500 g. The mixture was again homogenized and then stored in
a closed plastic or Teflon container. It was allowed to age at room
temperature for 4 to 35 days.
EXAMPLES 27-32
Preparation of ECR-32
A sodium aluminate solution was prepared by dissolving 59 g. NaOH in 100
ml. distilled water. To this solution 75 g. of aluminum trihydrate
(Al.sub.2 O.sub.3.3H.sub.2 O;156.01 g./mole; ALCOA C-31) was added and the
solution was heated with stirring on a hot plate/magnetic stirrer to a
mild boil until the alumina dissolved. The solution was then cooled to
room temperature and distilled water added to a final weight of 250 g.
A series of reactant gels were prepared having the stoichiometry:
3.6 TPA.sub.2 O:1.2 Na.sub.2 O:Al.sub.2 O.sub.3 :18 SiO.sub.2 :275 H.sub.2
O:0.99 Na.sub.2 SO.sub.4.
All gels were identically prepared except for the age time of the nucleant
seeds. To a 250 ml. plastic beaker were added, while mixing with a
spatula, 43.2 g. of 40% colloidal silica (HS-40, dupont Ludox; 40 wt. %
SiO.sub.2), 11.6 g. nucleant seeds (Example 26), 63.7 g. of aq. 40% TPAOH,
5.17 g. sodium aluminate solution as made above, 7.44 g. of 50% Al.sub.2
(SO.sub.4).sub.3.17H.sub.2 O solution, and enough distilled water to bring
the total weight of mixture to 135 g. The white gels were transferred to a
blender and thoroughly homogenized. The gels were then placed in 125 ml.
Teflon bottle and reacted in an air oven at 100.degree. C.
Samples were taken periodically, filtered and washed with distilled water.
Crystallization was followed by powder X-ray diffraction until completed.
The following table lists the crystallization time of each example and
clearly shows the preferred seed age time of 9 days or greater for room
temperature aged seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =15.
TABLE 4
______________________________________
Crystallization
Example # Seed age (days)
time (days)
______________________________________
27 4 10
28 9 8
29 14 8
30 18 7
32 25 7
33 35 7
______________________________________
EXAMPLE 34
Preparation of Nucleant Seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =20
A nucleant seed solution of stoichiometry,
13.33 Na.sub.2 O:Al.sub.2 O.sub.3 :20 SiO.sub.2 :267 H.sub.2 O,
was prepared by first preparing a sodium aluminate solution by dissolving
43.1 g. NaOH in 100 ml. distilled water. To this solution 11.2 g. of
alumina trihydrate (Al.sub.2 O.sub.3.3H.sub.2 O;156.01 g./mole; ALCOA
C-31) was added and the solution was heated with stirring on a hot
plate/magnetic stirrer until the alumina dissolved. The solution was
cooled to room temperature. To a one liter blender was added 301.7 g. of N
brand sodium silicate solution (P.Q. Corp. 8.9% Na.sub.2 O;26.7%
SiO.sub.2) and 40 g. of distilled water. With vigorous stirring the sodium
aluminate solution was slowly poured in and then rinsed in with distilled
water. Enough distilled water was then added to bring the total weight of
the mixture to 500 g. The mixture was again homogenized and then stored in
a closed plastic or Teflon container. It was allowed to age at room
temperature for 4 to 57 days.
EXAMPLES 35-40
Preparation of ECR-32.
A sodium aluminate solution was prepared by dissolving 59 g. NaOH in 100
ml. distilled water. To this solution 75 g. of aluminum trihydrate
(Al.sub.2 O.sub.3.3H.sub.2 O;156.01 g./mole; ALCOA C-31) was added and the
solution was heated with stirring on a hot plate/magnetic stirrer to a
mild boil until the alumina dissolved. The solution was then cooled to
room temperature and distilled water added to a final weight of 250 g.
A series of reactant gels were prepared having the stoichiometry:
3.6 TPA.sub.2 O:1.2 Na.sub.2 O:Al.sub.2 O.sub.3 :18 SiO.sub.2 :275 H.sub.2
O:0.99 Na.sub.2 SO.sub.4.
All gels were identically prepared except for the age time of the nucleant
seeds. To a 250 ml. plastic beaker were added, while mixing with a
spatula, 42.9 g. of 40% colloidal silica (HS-40, dupont Ludox; 40 wt. %
SiO.sub.2), 12.1 g. nucleant seeds (Example 34), 63.7 g. of aq. 40% TPAOH,
5.17 g. sodium aluminate solution as made above, 7.44 g. of 50% Al.sub.2
(SO.sub.4).sub.3.17H.sub.2 O solution, and enough distilled water to bring
the total weight of mixture to 135 g. The white gels were transferred to a
blender and thoroughly homogenized. The gels were then placed in 125 ml.
Teflon bottle and reacted in an air oven at 100.degree. C.
Samples were taken periodically, filtered and washed with distilled water.
Crystallization was followed by powder X-ray diffraction until completed.
The following table lists the crystallization time of each example and
clearly shows that seeds having SiO.sub.2 /Al.sub.2 O.sub.3 =20 are not as
effective as seeds prepared with SiO.sub.2 /Al.sub.2 O.sub.3 <20.
TABLE 5
______________________________________
Crystallization
Example # Seed age (days)
time (days)
______________________________________
35 4 24
36 9 21
37 14 18
38 18 14
39 25 13
40 57 10
______________________________________
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